Acoustic pulse-echo imaging tools are known in the art. The acoustic pulse-echo imaging tool usually comprises a rotating head on which is mounted a piezoelectric element transducer. The transducer periodically emits an acoustic energy pulse on command from a controller circuit in the tool. After emission of the acoustic energy pulse, the transducer can be connected to a receiving circuit, generally located in the tool, for measuring a returning echo of the previously emitted acoustic pulse which is reflected off the borehole wall. By processing the reflected signal, it is possible to infer something about the acoustic impedance characterizing the near-borehole environment. Specifically, changes in acoustic impedance are diagnostic of the quality of cement bonding between casing and the earth formation.
To detect possible defective cement bonds, the received signal has to be processed to estimate the arrival times and amplitudes of a plurality of reflections that may be overlapping in time, varying widely in amplitudes, and highly reverberatory in nature. The present disclosure is directed towards a method which estimates the arrival times and amplitudes of a plurality of reflections under such conditions.